Method and apparatus for preventing the spread of fire



E. E. FREE.

METHODAND APPARATUS FOR PREVENTING THE S PREAD OF FIRE. APPLICATION min JULY 5.1917.

. 1,344,630. Patented June 29, 1920.

8mm gala/M 6/ 3140 $13 A attovnua/ UNITED STATES PATENT OFFICE.

EDWARD E. FREE, OF BALTIMORE, MARYLAND, ASSIGNOR T NATIONAL SULPHUR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD AND APPARATUs FOR PREVENTING- THE SPREAD OF FIRE.

1,344,630, Specification of Letters Patent.

Patented June 29, 1920.

Application filed July 5, 1917. Serial No. 178,657.

To all whom it may concern:

Be it known that I, EDWARD E. FREE, a citizen of the United States, and a resident of Baltimore, in the State of Maryland,

ranged to stop the progress of an explosive fire through a screw conveyer, but it is obvious that the invention is not to be confined to this particular type of machine or to have invented certain new and useful Imthe method of application illustrated. By

provements in Methods and Apparatus for means of obvious modifications the inven- Preventing the Spread of Fire, of which tion can be applied to all forms of conveythe following is a specification. ing, hoisting, drying, grinding, bagging This invention provides a new and imand storing machinery; to machinery emproved method of, and apparatus for, apployed in nearly all chemical processes; to

plyin carbon dioxid gas to the control of firesstarte sions 'occurrlng 1n mixtures of air with inflammable dust or vapors.

It is well known that air laden with inmine galleries or. chambers; to a series of ad acent rooms for storage or process work;

7 and in fact, to any and all places and installations where explosive mixtures of dust flammable dust, as, for instance with coal or gases exist normally or may exist occadust or with finely powdered sulfur, is exsionally. plosive and that mixtures of inflammable In the drawing, the conveyer isassumed vapors as, for instance, gasolene, with the partly full of a dusty material, as for .inproper proportion of air are also explosive. stance, powdered sulfur, which material is In many cases the larger part of the damage propelled by the rotation of the conveyer resulting from such explosions is not due to actual breakage caused by the disrupting force of the explosion itself but is due to the fire which accompanies or follows the explosion and which is spread by it. It has been observed frequently that coincident with the explosion a wave of fire passes with extreme rapidity through the adjacent dustladen or vapor-laden air and that destructive fire is spread in this way from room to room of a plant or from one machine or machine-part to another.

One of the principal objects of this invention is to restrict an explosion occurring in inflammable dust or vapors, the resulting fire, and the damage by both the explosion and the fire to the particular machine, room, or other locus at which the explosion occurs.

Another important object of the invention is to provide a supply of carbon dioxid or other inert gas adapted to be suddenly released by the force of the explosion and to direct said released gas toward and into the place of explosion.

Another object of the invention is to store an inert gas under pressure, and to provide means by which said gas will be suddenly released by the force of the explosion and directed toward the source of the explosion and in a direction opposite to the spread of the fire.

There are other important objects and ad vantages of the invention, all of which will appear hereinafter.

The drawing shows the invention arin the direction shown by the arrow. The box A may be any sort of receptacle in which the dusty material is received preparatory to its progress through the conveyer A'. For instance, it may be the discharge hopper of a grinding mill. The box B may be any sort of receptacle into which the conveyer discharges the dusty material and from which the dusty material is continuously removed. For instance, it may be the lower boot of'an elevator. Dust explosions are particularly likely to occur in A, in .certain kinds of grinding mills. Under ordinary conditions the conveyer is never entirely full of material and the air in the space above the filled portion of the conveyer is ordinarily well charged with dust. Accordingly when an explosion takes place in A the fire-wave from this explosion passes rapidly through the conveyer and enters B, from whence it may spread to other machines, as for instance, up an elevator.

By means of this invention the propagation of the fire-wave from A to B through l) is kept filled with carbon dioxid gas under moderate pressure, say 50 to 300 pounds per square inch. Attached to the explosion door it are electric switch points F so arranged that the electric A circuit is closed when the door is opened. This same circuit communicates with the quick-opening valve C which valve is arranged to open instantaneously whenever the circuit is closed. A solenoid G is in circuit with the switch F, and upon the opening of the door E the solenoid is energized and releases the latch G. The pressure of the gas in the tank D then opens e valve C. It will be understood that any form of electrical or other device may be used for releasing the valve C.

An explosion occurring in the box A will blow open the door or valve E and thereby close the switch F and energize the solenoid G. Upon the release of the valve C the gas from the tank D will blow violently through the conveyer in the direction of the firewave. The released gas will not only beat back the fire-wave by the violence of its contrary movement, but also because of the effect of carbon dioxid in smothering combustion, it will extinguish any fire which may have started in the conveyer or in the box A. The fire having been extinguished, the door E and the valve C may be closed by hand, the tank D refilled with carbon dioxid gas (conveniently from the cylinders of compressed gas easily obtainable on the market) and the apparatus is again ready for service. Because of the harmless nature of carbon dioxid gas no damage results from the extinguishing of fires by this method whereas the damage by water alone is always great when water or aqueous solutions are employed as extinguishing agents.

The size of the tank D and of the release valve 0 and the working pressure of carbon dioxid gas in the tank D must be such as to conform with the size and nature of the machinery which is to be protected. The amount of the gas released must be sufiicient to create a strong gust of gas through the conveyer or equivalent machine and to fill substantially all of it with the inert gas. Similarly the precise arrangement of the explosion door, the actuating switch, the release valve, etc., may vary according to circumstances.

It should be noted that this apparatus is adapted to operateon any other kind of signal in place of, or in addition to, the blowing out of the explosion door. Thus it may be arranged to open on the melting of a fusible link H or on pressure of an electric button. Any two or more of these devices may be attached to the same operating circuit. Since the damage produced by carbon dioxid gas is usually m'l the accidental opening of the release valve is not a serious matter, as is the accidental discharge of extin uishing apparatus depending on water. accordingly the release apparatus may be made much more sensitive than is safe with sprinkler releases and the like.

It is manifest that the carbon dioxid gas is stored and maintained under pressure.

It is used only when needed, that is, when an explosion has occurred. It is further to be noted that when the gas is released there is a wave or rush of gas toward and into the fire and preferably in a direction opposite to the direction of the fire-wave. This serves to stop the fire by the force or violence of its movement, as well as by the smothering effect, due to the nature of the gas.

WVhile the invention has been described particularly for the use of carbon dioxid gas, it is not limited to the use of this agent. It includes the use of any other substances or mixture of substances not capable of supporting combustion and which produce or may be made to produce gases so as to operate as described, and produce the desired result. The invention is described herein as operating by means of an electric circuit between the explosion door and the release valve, but it is not to be limited to the use of electricity as a means of transmission of the impulse resulting from the explosion. The invention includes the use of any form of device or devices or other means capable of transmitting the release impulse quickly from the point of explosion to the point of gas release.

What I claim is:

1. The method of preventing the spread of fire, resulting from explosions, consisting in storing an inert gas under pressure, and releasing said gas immediately following the explosion and directing said released gas into the fire area and in a direction opposite to the direction of the fire-wave developed by said explosion, whereby the gase ous wave will oppose the movement of the fire-wave.

2. The method of preventing the spread of fire resulting from explosions, consisting in storing carbon dioxid gas under pressure, and releasing said gas immediately following the explosion and directing said released gas into the fire area and in a direction 0pposite to the direction of the fire-wave developed by said explosion, whereby the gaseous wave will oppose the movement of the fire-wave.

3. An apparatus for preventing the spread of fire due to an explosion, comprising a pressure tank adapted to hold an inert gas under pressure, a valve for said tank, means adapted to be operated by an explosion to open said valve, and means connected to said tank and adapted to direct the released gas toward the point of explosion and in a direction opposite to the direction of the fire wave developed by said explosion, whereby the aseous wave will oppose the movement of the fire wave.

4. An apparatus for preventing the spread of fire due to an explosion, comprising a tank adapted to hold an inert gas under pressure, a valve for said tank, a chamher, an explosion door for said chamber, means adapted to be operated by said door 5 to open said valve to release the gas and for directing it into the fire area in a direction opposite to the direction of the fire Wave developed by the explosion, and means connecting said tank to the chamber provided With the explosion door. 10

In testimony whereof I hereunto afiix my signature.

EDWARD E. FREE. 

